Nitric oxide (NO) is integral to many biological processes including the control of blood pressure, protection against microbial infection and neurotransmission. Additionally, it appears to be a potent cytotoxin to tumor cells. Among its mechanisms of action on malignant cells, nitric oxide appears to inhibit DNA synthesis and mitochondrial respiration in vitro. It induces programmed cell death or apoptosis in these cells.
Unfortunately, NO itself is difficult to administer as it is a highly reactive gas. It also causes hypotension if administered systemically. These limitations have prevented its use to date as an antineoplastic agent.
Several attempts have been made to formulate a pharmaceutical containing NO in the form of a prodrug. This method has not been successful as the prodrugs created to date are cleaved by ubiquitously available enzymes resulting in systemic release of NO. This causes hypotension and precludes the ability of these compounds to be used as therapeutics.
Methods of delivering NO directly to a specific cell type, such as a cancer cell, are needed that are capable of delivery without systemic release of NO.